I disassembled my leveling box to replace the stripped (rusted threads) leveling screw. I dont remember the specific steps but do remember disassembly was quite easy. Based on what I remember about the internals in the leveling box, I believe it more likely the male and female threaded portions of the leveling assembly are rusted together. Disassembling the leveling box should confirm that. The manual will show disassembly if it is not obvious.
TB in MN